The invention relates to a process for printing letters and/or patterns on an article of non-paper material, such as plastics, glass, metal. More particularly, the invention relates to a process for the clear and lasting reproduction of letters and/or patterns on an article of non-paper material, which otherwise would be difficult to print on.
It is known in the art that letters and patterns are printed on plastic containers and the like by silk screening or hot stamping. These processes are alternative, and have never before been combined. Silk screening provides a smooth transfer of ink; especially when a rotary screen is employed, the letter or pattern types are kept safe from detrimental deformation, thereby resulting in the sharp and finely-defined reproduction of letters and/or patterns. As compared with the hot stamping printing, silk screening lacks metallic gloss and smooth touch. On the other hand, although hot stamping offers good surface lustre and rich appearance, these advantages tend to be offset by the difficulty in printing. In hot stamping, a stamping foil having an adhesive layer on one side is laid over the article with its adhesive side facing the article. The article has a base film upon it. Raised heated printing dies are applied onto the layers, wherein the metal relief heated to 120.degree. C. to 130.degree. C. is pressed in one stroke at the pressure from about 2 to about 4 kilograms per square centimeter. Under the influence of heat and pressure the synthetic resin content employed tends to melt and become sticky, thereby tending to stick to and fill up the printing dies. In this situation sharp reproduction is impossible. In addition, plastic moulded articles have variations in shape and size, in the range of a given tolerance. This necessitates individual adjustment with printing articles. A further difficulty is derived from the uneven surface of certain types of articles such as bottles, in which the printing tends to be non-uniform due to the unequal contact of the printing dies with the surface of the article.
The present invention aims at solving the problems pointed out, and provides an improved process of printing letters and/or patterns on an article of non-paper material with sharply-defined figures and permanent reproduction thereof.